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authorZi Yan <zi.yan@cs.rutgers.edu>2017-09-09 02:11:01 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-09-09 04:26:45 +0300
commit84c3fc4e9c563d8fb91cfdf5948da48fe1af34d3 (patch)
treefc028524f9272c5ba1690d18937ebfc0bf0a0f9e /mm
parent616b8371539a6c487404c3b8fb04078016dab4ba (diff)
downloadlinux-84c3fc4e9c563d8fb91cfdf5948da48fe1af34d3.tar.xz
mm: thp: check pmd migration entry in common path
When THP migration is being used, memory management code needs to handle pmd migration entries properly. This patch uses !pmd_present() or is_swap_pmd() (depending on whether pmd_none() needs separate code or not) to check pmd migration entries at the places where a pmd entry is present. Since pmd-related code uses split_huge_page(), split_huge_pmd(), pmd_trans_huge(), pmd_trans_unstable(), or pmd_none_or_trans_huge_or_clear_bad(), this patch: 1. adds pmd migration entry split code in split_huge_pmd(), 2. takes care of pmd migration entries whenever pmd_trans_huge() is present, 3. makes pmd_none_or_trans_huge_or_clear_bad() pmd migration entry aware. Since split_huge_page() uses split_huge_pmd() and pmd_trans_unstable() is equivalent to pmd_none_or_trans_huge_or_clear_bad(), we do not change them. Until this commit, a pmd entry should be: 1. pointing to a pte page, 2. is_swap_pmd(), 3. pmd_trans_huge(), 4. pmd_devmap(), or 5. pmd_none(). Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: David Nellans <dnellans@nvidia.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Minchan Kim <minchan@kernel.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/gup.c22
-rw-r--r--mm/huge_memory.c65
-rw-r--r--mm/memcontrol.c5
-rw-r--r--mm/memory.c12
-rw-r--r--mm/mprotect.c4
-rw-r--r--mm/mremap.c2
6 files changed, 97 insertions, 13 deletions
diff --git a/mm/gup.c b/mm/gup.c
index 33d651deeae2..76fd199aaae2 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -234,6 +234,16 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma,
return page;
return no_page_table(vma, flags);
}
+retry:
+ if (!pmd_present(*pmd)) {
+ if (likely(!(flags & FOLL_MIGRATION)))
+ return no_page_table(vma, flags);
+ VM_BUG_ON(thp_migration_supported() &&
+ !is_pmd_migration_entry(*pmd));
+ if (is_pmd_migration_entry(*pmd))
+ pmd_migration_entry_wait(mm, pmd);
+ goto retry;
+ }
if (pmd_devmap(*pmd)) {
ptl = pmd_lock(mm, pmd);
page = follow_devmap_pmd(vma, address, pmd, flags);
@@ -247,7 +257,15 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma,
if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
return no_page_table(vma, flags);
+retry_locked:
ptl = pmd_lock(mm, pmd);
+ if (unlikely(!pmd_present(*pmd))) {
+ spin_unlock(ptl);
+ if (likely(!(flags & FOLL_MIGRATION)))
+ return no_page_table(vma, flags);
+ pmd_migration_entry_wait(mm, pmd);
+ goto retry_locked;
+ }
if (unlikely(!pmd_trans_huge(*pmd))) {
spin_unlock(ptl);
return follow_page_pte(vma, address, pmd, flags);
@@ -424,7 +442,7 @@ static int get_gate_page(struct mm_struct *mm, unsigned long address,
pud = pud_offset(p4d, address);
BUG_ON(pud_none(*pud));
pmd = pmd_offset(pud, address);
- if (pmd_none(*pmd))
+ if (!pmd_present(*pmd))
return -EFAULT;
VM_BUG_ON(pmd_trans_huge(*pmd));
pte = pte_offset_map(pmd, address);
@@ -1534,7 +1552,7 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
pmd_t pmd = READ_ONCE(*pmdp);
next = pmd_addr_end(addr, end);
- if (pmd_none(pmd))
+ if (!pmd_present(pmd))
return 0;
if (unlikely(pmd_trans_huge(pmd) || pmd_huge(pmd))) {
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 937f007794dd..b82585eabe85 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -928,6 +928,23 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
ret = -EAGAIN;
pmd = *src_pmd;
+
+#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
+ if (unlikely(is_swap_pmd(pmd))) {
+ swp_entry_t entry = pmd_to_swp_entry(pmd);
+
+ VM_BUG_ON(!is_pmd_migration_entry(pmd));
+ if (is_write_migration_entry(entry)) {
+ make_migration_entry_read(&entry);
+ pmd = swp_entry_to_pmd(entry);
+ set_pmd_at(src_mm, addr, src_pmd, pmd);
+ }
+ set_pmd_at(dst_mm, addr, dst_pmd, pmd);
+ ret = 0;
+ goto out_unlock;
+ }
+#endif
+
if (unlikely(!pmd_trans_huge(pmd))) {
pte_free(dst_mm, pgtable);
goto out_unlock;
@@ -1599,6 +1616,12 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
if (is_huge_zero_pmd(orig_pmd))
goto out;
+ if (unlikely(!pmd_present(orig_pmd))) {
+ VM_BUG_ON(thp_migration_supported() &&
+ !is_pmd_migration_entry(orig_pmd));
+ goto out;
+ }
+
page = pmd_page(orig_pmd);
/*
* If other processes are mapping this page, we couldn't discard
@@ -1810,6 +1833,25 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
preserve_write = prot_numa && pmd_write(*pmd);
ret = 1;
+#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
+ if (is_swap_pmd(*pmd)) {
+ swp_entry_t entry = pmd_to_swp_entry(*pmd);
+
+ VM_BUG_ON(!is_pmd_migration_entry(*pmd));
+ if (is_write_migration_entry(entry)) {
+ pmd_t newpmd;
+ /*
+ * A protection check is difficult so
+ * just be safe and disable write
+ */
+ make_migration_entry_read(&entry);
+ newpmd = swp_entry_to_pmd(entry);
+ set_pmd_at(mm, addr, pmd, newpmd);
+ }
+ goto unlock;
+ }
+#endif
+
/*
* Avoid trapping faults against the zero page. The read-only
* data is likely to be read-cached on the local CPU and
@@ -1875,7 +1917,8 @@ spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
{
spinlock_t *ptl;
ptl = pmd_lock(vma->vm_mm, pmd);
- if (likely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd)))
+ if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
+ pmd_devmap(*pmd)))
return ptl;
spin_unlock(ptl);
return NULL;
@@ -1993,14 +2036,15 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
struct page *page;
pgtable_t pgtable;
pmd_t _pmd;
- bool young, write, dirty, soft_dirty;
+ bool young, write, dirty, soft_dirty, pmd_migration = false;
unsigned long addr;
int i;
VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
- VM_BUG_ON(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd));
+ VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
+ && !pmd_devmap(*pmd));
count_vm_event(THP_SPLIT_PMD);
@@ -2025,7 +2069,16 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
return __split_huge_zero_page_pmd(vma, haddr, pmd);
}
- page = pmd_page(*pmd);
+#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
+ pmd_migration = is_pmd_migration_entry(*pmd);
+ if (pmd_migration) {
+ swp_entry_t entry;
+
+ entry = pmd_to_swp_entry(*pmd);
+ page = pfn_to_page(swp_offset(entry));
+ } else
+#endif
+ page = pmd_page(*pmd);
VM_BUG_ON_PAGE(!page_count(page), page);
page_ref_add(page, HPAGE_PMD_NR - 1);
write = pmd_write(*pmd);
@@ -2044,7 +2097,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
* transferred to avoid any possibility of altering
* permissions across VMAs.
*/
- if (freeze) {
+ if (freeze || pmd_migration) {
swp_entry_t swp_entry;
swp_entry = make_migration_entry(page + i, write);
entry = swp_entry_to_pte(swp_entry);
@@ -2143,7 +2196,7 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
page = pmd_page(*pmd);
if (PageMlocked(page))
clear_page_mlock(page);
- } else if (!pmd_devmap(*pmd))
+ } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
goto out;
__split_huge_pmd_locked(vma, pmd, haddr, freeze);
out:
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6532b219b222..f1f3f5b41155 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4664,6 +4664,11 @@ static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
struct page *page = NULL;
enum mc_target_type ret = MC_TARGET_NONE;
+ if (unlikely(is_swap_pmd(pmd))) {
+ VM_BUG_ON(thp_migration_supported() &&
+ !is_pmd_migration_entry(pmd));
+ return ret;
+ }
page = pmd_page(pmd);
VM_BUG_ON_PAGE(!page || !PageHead(page), page);
if (!(mc.flags & MOVE_ANON))
diff --git a/mm/memory.c b/mm/memory.c
index 13ee83b43878..886033b95fd2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1065,7 +1065,8 @@ static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src
src_pmd = pmd_offset(src_pud, addr);
do {
next = pmd_addr_end(addr, end);
- if (pmd_trans_huge(*src_pmd) || pmd_devmap(*src_pmd)) {
+ if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
+ || pmd_devmap(*src_pmd)) {
int err;
VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, vma);
err = copy_huge_pmd(dst_mm, src_mm,
@@ -1326,7 +1327,7 @@ static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
- if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
+ if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
if (next - addr != HPAGE_PMD_SIZE) {
VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
@@ -3911,6 +3912,13 @@ static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
pmd_t orig_pmd = *vmf.pmd;
barrier();
+ if (unlikely(is_swap_pmd(orig_pmd))) {
+ VM_BUG_ON(thp_migration_supported() &&
+ !is_pmd_migration_entry(orig_pmd));
+ if (is_pmd_migration_entry(orig_pmd))
+ pmd_migration_entry_wait(mm, vmf.pmd);
+ return 0;
+ }
if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
return do_huge_pmd_numa_page(&vmf, orig_pmd);
diff --git a/mm/mprotect.c b/mm/mprotect.c
index bd0f409922cb..a1bfe9545770 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -149,7 +149,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
unsigned long this_pages;
next = pmd_addr_end(addr, end);
- if (!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)
+ if (!is_swap_pmd(*pmd) && !pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)
&& pmd_none_or_clear_bad(pmd))
continue;
@@ -159,7 +159,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
mmu_notifier_invalidate_range_start(mm, mni_start, end);
}
- if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
+ if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
if (next - addr != HPAGE_PMD_SIZE) {
__split_huge_pmd(vma, pmd, addr, false, NULL);
} else {
diff --git a/mm/mremap.c b/mm/mremap.c
index 7395564daa6c..cfec004c4ff9 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -223,7 +223,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
if (!new_pmd)
break;
- if (pmd_trans_huge(*old_pmd)) {
+ if (is_swap_pmd(*old_pmd) || pmd_trans_huge(*old_pmd)) {
if (extent == HPAGE_PMD_SIZE) {
bool moved;
/* See comment in move_ptes() */